Dispersion of Sn and SnO on carbon anodes

Sn and SnO were supported on large surface-area synthetic graphite (KS6) to obtain composite materials with improved electrochemical performance relative to bulk Sn and SnO. In general the composites are superior to the mechanical mixtures of KS6 and Sn (or SnO) of similar overall compositions in many performance areas. The Sn–KS6 composites increase the reversible capacity of graphite at some expense of the cyclability. It was observed that Sn could also contribute to the irreversible capacity loss in the first cycle, probably through a mechanism similar to solid electrolyte interface (SEI) formation on carbonaceous surfaces. The KS6–SnO composites have good reversible capacities, rate capability and cycle life, although their irreversible capacity losses in the first cycles are necessarily higher because of the requisite electro-reduction reaction to convert the oxide precursor into Sn-based Li storage compounds. The observation of specific capacities that are larger than the weighted sums of the capacities of SnO and graphite suggests the presence of synergistic interaction between the two constituents.